1. Field of the Invention
The present invention relates to a molded part made of foamed thermoplastic resin employed as a protector or the like for an automotive wire harness and a method of fabricating the same.
2. Description of the Prior Art
A wire harness for wiring in an automotive electric system is protected by a protector 100 shaped as shown in FIGS. 8A and 8B, for example, which has an opening and closing lid 101 on one side surface thereof so as not to be damaged by a flash formed by punching in a press molded vehicular body. Such a protector 100 includes lock portions 102 for fixing the opening and closing lid 101 in a closed state after the wire harness is housed in the protector 100, and a bolting portion 103 for fixing the protector 100 to the vehicular body.
There has been a need for weight reduction of automotive vehicles for various reasons, and the protector 100 is no exception. In general, the above-mentioned protector 100 is fabricated by injection molding using thermoplastic resin such as polypropylene. One of the approaches to reduce the weight of a molded part of thermoplastic resin is to foam the molded part. Such a foamed molded part is achieved by adding a foaming agent to thermoplastic resin, plasticizing the thermoplastic resin, and injecting the plasticized thermoplastic resin into a mold.
Although required to be reduced in weight, the protector 100 shown in FIGS. 8A and 8B includes local areas required to have a strength higher than that of the other areas, such as the lock portions 102 and bolting portion 103. However, when the molded part of resin is foam molded in the conventional manner such as the protector 100, foams are present in the resin forming the lock portions 102 and the bolting portion 103, resulting in an insufficient strength of the lock portions 102 and the bolting portion 103.